The long-term goal of this project is a small molecule therapeutic of benefit to patients with rheumatoid arthritis (RA), which will act by reducing the inflammatory response triggered by macrophage migration inhibitory factor (MIF). RA afflicts up to 4 million people in the U.S., and the healthcare and indirect costs of this disease are significant. While several treatments are available, none of them are 100% effective and some of them lose effectiveness with time. The precise etiology of RA is not completely understood, but it is well-established that the disease is caused by inflammation and angiogenesis in the synovial lining of the joints, leading to joint destruction and the outgrowth of the invasive pannus. MIF has been implicated in the immunopathology of RA in clinical and preclinical studies, thus compounds which inhibit MIF activity may provide benefit in this disease. In a pilot study, a high-throughput screening assay that takes advantage of the vestigial (non-physiologic) tautomerase activity of MIF was used to identify nine hits. Three of those hits also inhibit binding of MIF to its cognate receptor, a step which is critical in the biological activity of MIF. This screen will be expanded to a larger library, which is likely to yield additional novel small molecule inhibitors of MIF tautomerase activity that will become additional candidates for this Phase I project. In this Phase I project, a panel of biochemical and biological assays of MIF activity will be employed to further characterize and rank order hits based on inhibition of MIF:receptor binding and subsequent cellular activation. These include assays for MIF-triggered ERK1/2 phosphorylation, inhibition of p53-induced apoptosis, and secretion of inflammatory cytokines and matrix- degrading enzymes, all of which contribute to the inflammation and outgrowth of pannus in RA joints. The final product of this Phase I project will be a panel of hits that inhibit MIF-driven cellular activation pathways that contribute to the immunopathology of RA. These hits will be candidates for a subsequent Phase II project, which will include medicinal and computational chemistry efforts to produce leads with higher potency and more favorable drug-like properties, as well as in vivo studies using an animal model of RA. Upon successful completion of Phase II objectives, we will commence pre-clinical and clinical development efforts in partnership with one of a number of large, well-established pharmaceutical firms who share our vision for new therapeutics that will reduce MIF-induced immunopathology in RA. PUBLIC HEALTH RELEVANCE: The goal of this project is to identify and develop small molecule therapeutic compounds for the treatment of rheumatoid arthritis (RA), a disease which afflicts up to 4 million people in the US. These compounds will be identified by their ability to inhibit the inflammatory component of RA that is caused by the cytokine macrophage migration inhibitory factor (MIF). Since MIF acts upstream in the inflammatory cascade in RA, inhibition of this activity will address many of the downstream effector pathways that are ultimately responsible for joint destruction.